Radar Warning Receiver with Position and Velocity Sensitive Functions

ABSTRACT

A GPS enabled radar detector dynamically handles radar sources based upon previously-stored geographically-referenced information on such sources and data from the GPS receiver. The detector includes technology for determining the location of the detector, and comparing this location to the locations of known stationary sources, to improve the handling of such detections. The detector may ignore detections received in an area known to contain a stationary source, or may only ignore specific frequencies or may handle frequencies differently based upon historic trends of spurious police radar signals at each frequency. Notification of the driver will take on a variety of forms depending on the stored information, current operating modes, and vehicle speed.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a United States divisional application of U.S. Ser.No. 10/396,881, filed Mar. 25, 2004, which is a United States divisionalapplication of U.S. Ser. No. 09/889,656, filed Jul. 19, 2001 (with thedeclaration under Section 371(c)(4) filed Mar. 15, 2002), now U.S. Pat.No. 6,670,905, which is a U.S. National Phase of PCT/US00/16410 filedJun. 14, 2000, which claims benefit of and is a continuation-in-part ofboth U.S. Provisional Patent Application Ser. No. 60/139,097, filed Jun.14, 1999, and U.S. Provisional Patent Application Ser. No. 60/145,394,filed Jul. 23, 1999, all of which are hereby incorporated herein intheir entirety.

FIELD OF THE INVENTION

The present invention relates to radar warning receivers.

BACKGROUND OF THE INVENTION

Radar detectors warn drivers of the use of police radar, and thepotential for traffic citations if the driver exceeds the speed limit.The FCC has allocated several regions of the electromagnetic spectrumfor police radar use. The bands used by police radar are generally knownas the X, K and Ka bands. Each relates to a different part of thespectrum. The X and K bands are relatively narrow frequency ranges,whereas the Ka band is a relatively wide range of frequencies. By theearly 1990's, police radar evolved to the point that it could operatealmost anywhere in the 1600-megahertz wide Ka band. During that timeradar detectors kept pace with models that included descriptive nameslike “Ultra Wide” and “Super Wide.” More recently, police have begun touse laser (optical) systems for detecting speed. This technology wastermed LIDAR for “Light Detection and Ranging.”

Radar detectors typically comprise a microwave receiver and detectioncircuitry that is typically realized with a microprocessor or digitalsignal processor (DSP). Microwave receivers are generally capable ofdetecting microwave components in the X, K, and very broad Ka band. Invarious solutions, either a microprocessor or DSP is used to makedecisions about the signal content from the microwave receiver. Systemsincluding a digital signal processor have been shown to provide superiorperformance over solutions based on conventional microprocessors due tothe DSP's ability to find and distinguish signals that are buried innoise. Various methods of applying DSP's were disclosed in U.S. Pat.Nos. 4,954,828, 5,079,553, 5,049,885, and 5,134,406, each of which ishereby incorporated by reference herein.

Police use of laser has also been countered with laser detectors, suchas described in U.S. Pat. Nos. 5,206,500, 5,347,120 and 5,365,055, eachof which is incorporated herein by reference. Products are now availablethat combined laser detection into a single product with a microwavereceiver, to provide comprehensive protection.

The DSP or microprocessor in a modern radar detector is programmable.Accordingly, they can be instructed to manage all of the user interfacefeatures such as input switches, lights, sounds, as well as generatecontrol and timing signals for the microwave receiver and/or laserdetector. Early in the evolution of the radar detector, consumers soughtproducts that offered a better way to manage the audible volume andduration of warning signals. Good examples of these solutions are foundin U.S. Pat. Nos. 4,631,542, 5,164,729, 5,250,951, and 5,300,932, eachof which is hereby incorporated by reference, which provide methods forconditioning the response generated by the radar detector.

Methods for conditioning detector response are gaining importance,because there is an increasing number of signals present in the X, K,and Ka bands from products that are completely unrelated to policeradar. These products share the same regions of the spectrum and arealso licensed by the FCC. The growing number of such signals is rapidlyundermining the credibility of radar detector performance. Radardetectors cannot tell the difference between emissions from many ofthese devices and true police radar systems. As a result, radardetectors are increasingly generating false alarms, effectively “cryingwolf”, reducing the significance of warnings from radar detectors.

One of the earliest and most prevalent unrelated Microwave sources isthe automatic door system used in many commercial buildings such assupermarkets, malls, restaurants and shopping centers. The majority ofthese operate in the X-Band and produce signals virtuallyindistinguishable from conventional X-Band Police Radar. Other than thefact that door opening systems are vertically polarized, vs circularpolarization for police radar, there is no distinction between the twothat could be analyzed and used by a receiver design.

Until recently, virtually all of the door opening systems were designedto operate in the X-Band. As a result, radar detectors generallyannounced X-Band alerts far more often than K-Band. As these X-Band‘polluters’ grew in numbers, ultimately 99% of X-Band alerts were fromirrelevant sources. X-Band alerts became meaningless. The only benefitthat these sources offered the user was some assurance that the detectorwas actually capable of detecting radar. It also gave the user someintuition into the product's detection range. To minimize the annoyanceto users, most radar detector manufacturers added a filter-like behaviorthat was biased against X-Band sources. Many also added “Band priority”that was biased against X and in favor of bands that were less likely tocontain irrelevant sources such as K, Ka, and Laser. If signals in bothX and K Bands were detected, band prioritization would announce K, sinceit was more likely be a threat to the driver. In the last few years,K-Band door opening systems have also grown in number. This has reducedthe significance of the K-Band warning and further undercut the overallbenefit to the user of a radar detector.

Another unrelated microwave signal is generated by traffic managementsystems such as the ARTIMIS manufactured by TRW, used in Cincinnati,Ohio. ARTIMIS Stands for “Advanced Regional Traffic InteractiveManagement and Information System”, and reports traffic flow informationback to a central control center. Traffic congestion and other factorsare analyzed by the control center. Control center employees use thisinformation to formulate routing suggestions and other emergencyinformation, which they transmit to a large distribution of overhead androadside signs. In order to collect information on vehicle traffic, aroadside ARTIMIS station transmits an X-Band signal toward cars as theydrive by. The ARTIMIS source, unlike the X-Band door opener systems, isdistinguishable from police radar as it is not transmitted at a singlefixed frequency. As a result, it is possible to differentiate policeradar signals from sources such as ARTIMIS, and ignore ARTIMIS sourcesin newer detectors. Older detectors, however, do not incorporate thisfeature and could be obsolete in areas where ARTIMIS is in use.

Unrelated Microwave signals are also transmitted by a system called theRASHID VRSS. Rashid is an acronym for Radar Safety Brake CollisionWarning System. This electronic device warns heavy trucks and ambulancesof hazards in their path. A small number of these RASHID VRSS units havebeen deployed. They are categorized as a member of the ‘non-stationary’set of unrelated sources. As in the ARTIMIS example, detection of RASHIDcan be prevented.

Perhaps the biggest source of non-stationary unrelated sources is fromother radar detectors. These are sometimes referred to as “pollutingradar detectors,” and present a serious threat to some detectorproducts. An early example of this occurred in the mid 1980's when radardetectors using superhomodyne circuitry became popular. Such detectorsleak energy in the X-Band and K-bands and appeared as police radar toother detectors. A solution to this problem is described in U.S. Pat.No. 4,581,769, which is hereby incorporated by reference in itsentirety. A similar problem occurred in the early 1990's when the Kaband was widened. An unexpected result was that the wider Ka band thenalso detected harmonics of signals generated by local oscillators withinmany existing radar detectors. U.S. Pat. No. 5,305,007, which is herebyincorporated by reference in its entirety, describes a method forignoring these polluting detectors.

At this time, there are very few signal sources that can cause falselaser detections in comparison to the substantial list of falsemicrowave signals just described. However there are certain types ofequipment that can cause the amplifiers and detection circuitry used ina laser detector to generate a “false” detect. In particular, certainlocations near airports have been demonstrated to cause such problemsfor various laser detector products. As a result, selected airportenvironments are examples of stationary signals that produce false laserdetections.

As can be appreciated from the foregoing example, as sources ofunrelated signals continue to propagate, radar detectors mustcontinually increase in sophistication to filter unrelated sources andaccurately identify police radar. Each of these changes and enhancementshas the potential effect of obsoleting existing detectors that do notinclude appropriate countermeasures. Furthermore, some sources,particularly stationary door opener sources, at this time cannot befiltered economically, and thus threaten the usefulness of even the mostsophisticated modern radar detector.

During the 1980's, the functionality of radar detectors expanded intoother classes of driver notification. A system was developed thatrequired a special transmitter be placed on emergency vehicles, trains,and other driving hazards. The term ‘emergency radar’ was coined, and avariety of products were introduced that could detect thesetransmitters. One such solution was disclosed in U.S. Pat. No.5,559,508, which is hereby incorporated by reference herein in itsentirety. Another system was later introduced offering a larger class of‘hazard categories’ called the SWS system. Both emergency radar and SWSinvolve the transmission of microwave signals in the ‘K’ band. Suchsignals are considered to be a part of the group of signal types thatare intended to be detected by radar detectors.

A drawback of these warning systems is that stationary transmitters ofthese signals send the same message to drivers constantly, and become anuisance during daily commute. This is beneficial to ‘new’ driversreceiving the message for the first time. However these messages becomean annoyance to drivers who follow the same path to work everyday.

Thus, radar detector manufacturers are continually confronted with newproblems to solve, due to the variety of different types of unrelatedsources and their sheer numbers. The rate at which new or upgraded radardetector models are introduced continues to increase as manufacturerstry to evolve their products to manage the growing number of unrelatedsources. Meanwhile, the market for radar detectors is shrinking becauseconsumers are no longer interested in buying products that so quicklybecome obsolete.

SUMMARY OF THE INVENTION

The present invention overcomes these difficulties by providing a methodof operating a radar detector that aids in the management of unrelatedsources, and permitting the detector to dynamically improve its handlingof unrelated sources. As noted above, many non-stationary sources can beidentified and ignored using existing technology. However, manystationary sources cannot, as yet be effectively filtered economicallywith existing technology. Accordingly, the invention provides a radardetector that includes technology for determining the location of thedetector, and comparing this location to the locations of knownstationary sources, to improve the handling of such detections.

In one embodiment, a radar detector may ignore detections received in anarea known to contain a stationary source. In the specific embodimentdescribed below, substantially more sophisticated processing isperformed to determine whether and what actions to take in response to adetection.

The Global Positioning Satellite System (GPS) offers an electronicmethod for establishing current physical coordinates very accurately. Inthe detailed embodiment described below, a radar detector utilizes a GPSsystem to determine its current position. The detector also maintain alist of the coordinates of the known stationary source “offenders” innonvolatile memory. Each time a microwave or laser source is detected,it will compare its current coordinates to this list. Notification ofthe driver will take on a variety of forms depending on the setupconfiguration.

By adding GPS conditioning capabilities to a radar detector, thecombination becomes a new product category that is capable of rejectingsignals from any given location no matter what the nature of themicrowave/laser signals might be from that location. This will have adramatic effect on the usable life of the product and subsequent valueto its owner.

The above and other objects and advantages of the present inventionshall be made apparent from the accompanying drawings and thedescription thereof.

BRIEF DESCRIPTION OF THE DRAWING

The accompanying drawings, which are incorporated in and constitute apart of this specification, illustrate embodiments of the invention and,together with a general description of the invention given above, andthe detailed description of the embodiments given below, serve toexplain the principles of the invention.

FIG. 1 is an illustration of a vehicle receiving radar signals frompolice radar and from a number of unrelated sources, and furtherreceiving global positioning signals from a global positioningsatellite;

FIG. 2 is an electrical block diagram of a radar detection circuit inaccordance with principles of the present invention;

FIG. 3 is a illustration of a database structure used by the radardetection circuit of FIG. 2, for storing information radar signalsreceived or receivable from unrelated sources at a number of locations,as identified by cell coordinates;

FIG. 4 is an illustration of a database structure used for storinghistoric information on the locations of a vehicle carrying the radardetection circuit of FIG. 2, as identified by cell coordinates;

FIG. 5 is an illustration of a database structure used for storing flagsidentifying various conditions at a number of locations, as identifiedby cell coordinates;

FIG. 6A is a flow chart of the operations of the CPU of the radardetector of FIG. 2, carrying out principles of the present invention;

FIG. 6B is a flow chart of operations of the CPU of FIG. 2 in processingGPS information when GPS signals are being received;

FIG. 6C is a flow chart of operations of the CPU of FIG. 2 in updatingstored information when a radar signal is being received;

FIG. 6D is a flow chart of operations of the CPU of FIG. 2 in updatingstored information when a radar signal is not being received;

FIG. 6E is a flow chart of operations of the CPU of FIG. 2 in respondingto keypad activity to change operative mode of the GPS enabled radardetector; and

FIG. 6F is a flow chart of operations of the CPU of FIG. 2 in generatingaudible and visible responses based upon operating modes of the radardetector and the presence or absence of radar signals and storedinformation.

DETAILED DESCRIPTION OF SPECIFIC EMBODIMENTS

To provide background for the present invention, a summary of GPS(Global Positioning System) technology will now be provided. GPS is amature technology that provides a method for a GPS receiver to determineits relative location and velocity at any time. The (GPS) system is aworldwide constellation of 24 satellites and their ground stations. GPSreceivers on earth use ‘line of sight’ information from these satellitesas reference points to calculate positions accurate to a matter ofmeters. Advanced forms of GPS actually enable measurements to within acentimeter. The Global Positioning System consists of three segments: aspace segment of 24 orbiting satellites, a control segment that includesa control center and access to overseas command stations, and a usersegment, consisting of GPS receivers and associated equipment. Over timeGPS receivers have been miniaturized to just a few integrated circuitsand have become very economical.

An unfortunate side effect of the GPS system is that it can be used byenemy forces, as GPS signals can be picked up by any receiver includingboth domestic and foreign. When the United States Department of Defensedevised the GPS system they incorporated a feature that prevents highprecision measurements unless the receiver is equipped with specialmilitary ‘keys.’ This is accomplished with the intentional introductionof “noise” into the satellite's clock data which adds noise (orinaccuracy) into position calculations. The DOD sometimes also sendsslightly erroneous orbital data to the satellites, which is transmittedback to receivers on the ground. This intentional degradation isreferred to as “Selective Availability” or “SA” error. Militaryreceivers use a decryption key to remove the SA errors. As a result ofthe SA error, there are two classes of GPS service, “StandardPositioning Service (SPS) and “Precise Positioning System” (PPS.). Theseclasses are realized by having GPS satellites transmit two differentsignals: the Precision or P-code and the Coarse Acquisition or C/A-code.The P-code is designed for authorized military users and provides PPSservice. To ensure that unauthorized users do not acquire the P-code,the DOD can engage an encryption segment on the P-code calledanti-spoofing (AS). The C/A-code is designed for use by nonmilitaryusers and provides SPS service. The C/A-code is less accurate and easierto jam than the P-code. It is also easier to acquire, so militaryreceivers first track the C/A-code and then transfer to the P-code.Selective availability is achieved by degrading the accuracy of theC/A-code.

The precision of SPS is stated as providing 100-meter horizontal and 156meter vertical accuracy “95% of the time.” PPS is only available for theU.S. and allied military, certain U.S. Government agencies, and selectedcivil users specifically approved by the U.S. Government. PPS provides22 meters horizontal and 22.7 meters vertical accuracy 95% of the time.

Other than intentional errors inserted by the DOD, there are a varietyof other error sources that vary with terrain and other factors. GPSsatellite signals are blocked by most materials. GPS signals will notpass through buildings, metal, mountains, or trees. Leaves and junglecanopy can attenuate GPS signals so that they become unusable. Inlocations where at least four satellite signals with good geometrycannot be tracked with sufficient accuracy, GPS is unusable.

The “Differential GPS” system was developed in order to compensate forthe inaccuracy of GPS readings. A high-performance GPS receiver (knownas a reference station or beacon) is placed at a specific location; theinformation it receives is then compared to the receiver's location andcorrects the SA satellite signal errors. The error data is thenformatted into a correction message and transmitted to GPS users on aspecific frequency (300 kHz). A true or arbitrary set of coordinates areassigned to the position occupied by a reference GPS receiver. Thedifference between these and the coordinates received via GPS at thereference is a very close approximation to the SA error at nearby sites.This error is nearly identical to the error calculated by any nearby GPSreceiver. The reference site is sometimes referred to as a ‘beacon,’ asit constantly transmits these difference coordinates. A DPGS receiver isdesigned to receive both the GPS information and the beacon information.It generates a far more accurate estimate of its coordinates by applyingthe difference information to the GPS coordinates. The drawback to thisis that the remote and reference receivers may not be using the same setof satellites in their computations. If this is the case, and the remotereceiver incorporates the corrections, it may be accounting forsatellite errors that are not included in its own measurement data.These corrections can make the differential solution worse than theuncorrected GPS position. To prevent this error, an improved form ofdifferential GPS involves the derivation of the corrections to theactual measurements made at the reference receiver to each satellite. Byreceiving all of the corrections independently, the remote receiver canpick and choose which are appropriate to its own observations. Thismethod of DGPS is most widely used. Typically, the DGPS correctionsignal loses approximately 1 m of accuracy for every 150 km of distancefrom the reference station.

The availability of Beacons for DGPS systems elevate the very threatthat the SA error was intended to reduce. In the presence of suchnetworks, potentially hostile weapons systems using DGPS could bedeveloped relatively rapidly. For this reason and others, the SA errorhas diminished in military significance. The White House has Directedthat the S/A error be “Set to Zero” by the year 2006.

In the United States, the US Coast Guard (USCG) and Army Corps ofEngineers (ACE) have constructed a network of Beacon stations thatservice the majority of the eastern United States, the entire length ofboth coastlines, and the Great Lakes. Further plans exist to increasethe density of this network to provide dual redundant coveragethroughout the continental US by the end of the year 2000 for a varietyof applications including intelligent transportation system,infrastructure management, and public safety.

The Canadian Coast Guard (CCG) provides coverage in Canada for the St.Lawrence River, throughout the Great Lakes, and both coastlines. Intotal, there are over 160 stations operational worldwide with over 140sites proposed to come online within the next two years. Coveragecurrently exists in many other regions of the world including Europe,Asia, Australia, Africa, and South America.

The beacons perform the differential calculation and broadcasts thisinformation by modulating the data onto a 300 kHz signal transmitted bythe established network of Radiobeacons. The advantages of using theBeacon DGPS network include: (1) Free access to differential correctioninformation; (2) Long range signal which penetrates into valleys, andtravels around obstacles; (3) High quality differential correctionswhich are continuously monitored for integrity; and (4) Inexpensive userequipment.

The range of the 300 kHz signal is dependent upon a number of factorswhich include transmission power and conductivity of the surface overwhich the transmission is propagating. The Beacons within the globalnetwork broadcast at varying power. Typical broadcasting ranges forradiobeacons vary from as little as 35 nautical miles to as much as 300nautical miles. Signals broadcast by DGPS radiobeacons are integritymonitored by remote stations for quality of beacon transmission,differential corrections, and GPS positional information. In addition,government agencies concerned with public safety have made it theirmandate to ensure that beacon DGPS services are available 24 hours aday, 365 days a year. Performance requirements for marine applicationsdictate that an availability of 99% or greater is required if aparticular system is to be used as a sole means of navigation. The USCoast Guard and Army Corps of Engineers Beacon Network, for example,offer this high level of availability free of charge to all civilianusers.

There are other navigation systems in place, in addition to GPS, thatmerit review. LORAN-C is a ground-based radio navigation system. Itoperates on a frequency band of 90 kHz to 110 kHz (LF). It has anapproximate range of hundreds to thousands of miles, and an accuracy of0.25 nautical miles repeatable to 18-90 meters, with 95% confidence.Loran-C is a pulsed hyperbolic system that provides 0.25 nm predictableaccuracy, 18-90 m repeatable accuracy, 95% confidence and 99.7%availability. Loran-C provides coverage for the continental U.S. and itscoastal waters, the Great Lakes, and most of Alaska. Many othercountries are also involved in the providing of Loran-C (or Loran-like)services, or are in negotiations with their neighbors to expandcoverage. These countries include India, Norway, France, Ireland,Germany, Spain, Italy, Russia, China, Japan, the Philippines and others.

Omega is a low frequency band system with accuracy of 2 to 4 nauticalmiles with 95% confidence level. Developed by the United States, it isoperated in conjunction with six other nations. OMEGA is a very lowfrequency, phase comparison, worldwide radionavigation system

Tacan operates in the U.S. in a frequency band of 960 MHz-1215 MHz(UHF). It has a range of approximately 200 miles at high altitudes.TACAN is primarily used by U.S. and other military aircraft. TACAN radiostations are often co-located with civilian VOR systems allowingmilitary aircraft to operate in civil airspace. The system provides thepilot with relative bearing and distance to the radio beacon.

VOR operates in a frequency band of 108.0 MHz-117.95 MHz (VHF). It hasan approximate range of 250 miles, but accuracy as poor as 20 miles. VORis a beacon-based navigation system operated in the U.S. by the FederalAviation Administration (FAA) for civil aircraft navigation. When usedby itself, the system allows users to determine their azimuth from theVOR station without using any directional equipment. VOR stations areradio beacons that transmit two signals. The first, called the referencesignal, is transmitted with constant phase all around the transmitter.The second signal is phase shifted from the first depending on thecompass direction of the user from the station. A simple, inexpensivereceiver in the aircraft is used to determine the received phasedifference of the two signals, and from that information the directionof the aircraft from the transmitter. By using two VOR stations, aspecific location may be determined.

Of all the navigation systems mentioned, GPS offers better service, moreaccuracy, and more serviceable regions than any other approach. Thereare various classes of GPS service that improve accuracy at highercosts. These include the following categories: (1) Low-cost, singlereceiver SPS projects (100 meter accuracy); (2) Medium-cost,differential SPS code Positioning (1-10 meter accuracy); (3) High-cost,single receiver PPS projects (20 meter accuracy); (4) High-cost,differential carrier phase surveys (1 mm to 1 cm accuracy); and (5)High-cost, Real-Time-Kinematic (1 cm) with real time accuracyindications.

Referring now to FIG. 1, a vehicle 10 is illustrated in operation on aroadway, under exposure to radio frequency signals from a variety ofsources. These include the GPS satellite system, LORAN or OMEGA radiotowers, non-police sources of interference such as restaurant 16, andpolice radar signals from a radar gun 18. In accordance with principlesof the present invention, vehicle 10 is equipped with a radar detectorable to identify the present coordinates and/or velocity of the vehicle,e.g. using an associated GPS receiver or alternatively a receiver ofland-based signals such as LORAN. The radar detector is able to use thisinformation to enhance its decision-making abilities.

Referring now to FIG. 2, the radar detector 20 in accordance withprinciples of the present invention includes a fusion processor 22 forcontrolling all functions of the unit. Fusion processor receivesinformation on radar signals from a conventional microwave receiver 24,coupled to processor 22 via a digital signal processor (DSP) 26.Microwave receiver 24 and DSP 26 may utilize any of the techniquesdescribed above and in the above-referenced patents, for rejecting noiseand increasing discrimination between actual and spurious police radarsignals. Further, receiver 24 and DSP 26 maybe controlled by an optionalsecond CPU 25, which can enable additional signal evaluation beyond thatwhich is possible using a DSP.

Processor 22 is further connected to a laser detector 28 for detectingpolice LIDAR signals. Processor 22 is further connected to a GPSreceiver 32 and a separate differential GPS (DGPS) receiver 30, suchthat differential GPS methodologies may be used where beacon signals areavailable. Since the radar detector application described in this patentis not a candidate for military class service, it is not able to accessthe more accurate PPS. However it is considered a “civil user” and canuse the SPS without restriction.

Processor 22 executes a stored program, found in an electricallyerasable programmable read only memory (EEPROM) 34, flash memory, ormasked read only memory (ROM). The processor is programmed to manage andreport detected signals in various ways depending on its stored program.This programming includes functions for “detector responseconditioning,” as elaborated below, e.g., with reference to FIGS. 6Athrough 6D.

The radar detector further incorporates a user input keypad or switches36. Operational commands are conveyed by the user to processor 22 viathe keypad. Processor 22 is further connected to a display 38, which maycomprise one or more light emitting diodes for indicating various statusconditions, or in a more feature-rich device, may include analphanumeric or graphical display for providing detailed information toa user. A speaker 40 is also provided to enable processor 22 to deliveraudible feedback to a user under various alert conditions, as iselaborated below.

Processor 22 may further include an interface 44, such as an ODB IIcompliant interface, for connection to vehicle electronic systems 42that are built into the vehicle 10. Modern vehicles are being equippedwith standardized information systems using the so-called OBD IIstandard interface. This standard interface is described in an articleentitled ODB II Diagnostics, by Larry Carley, from Import Car, January1997, which is hereby incorporated herein by reference. Processor 22,using the OBD II standard interface 44, can obtain vehicle speed andother vehicle status information directly from the vehicle, and then mayuse this information appropriately as described in more detail below.

Processor 22 is further coupled to a Universal Serial Bus (USB)interface 46 that provides a means for uploading and downloadinginformation to and from processor 22. Specifically, USB interface 46 maybe used to automate the assimilation of coordinate information into datastructures in EEPROM 34, as described below with reference to FIGS. 3through 5. USB interface 46 may also be used to interface the detectorto a separate host computer or product application containing a largerstorage capacity than available from internal memory. Remote storagedevices may include any form of dynamically allocatable storage device(DASD) such as a hard disk drive, removable or fixed magnetic, opticalor magneto-optical disk drive, or removable or fixed memory card, or anydevice including a dynamic directory structure or table of contentsincluded in the storage format to permit dynamic storage allocation. Thehost computer or other connected device need not be visible to thedriver and may be in any convenient location, such as under the vehicledash.

Coordinate information can be stored, e.g., on a hard drive organizedwith an indexed database structure to facilitate rapid retrieval, andthe hard drive may include a special purpose processor to facilitaterapid retrieval of this information.

Where a general purpose host computer is connected via the USBinterface, it will likely be based on a higher scale CPU chip and thusbe able to efficiently carry out complex coordinate comparison taskssuch as are described below, and such tasks may be delegated to the hostCPU rather than carried out in fusion processor 22. The host CPU canalso anticipate the need for information about particular coordinatesbased upon vehicle movements, and respond by retrieving records withinproximity of the current location for ready delivery to fusion processor22. The host computer can also provide navigational functions to thedriver, potentially using stored signal information and flag bits toprovide the user with location-specific information about drivinghazards and potential police stakeout locations.

Signal information may also be downloaded from other hosts, for example,a connection may be established directly via the USB interface to anInternet site carrying signal information, as is now done in a text format the Internet site speedtrap.com. An indirect Internet connection mayalso be established via a host computer. Furthermore, connections may beestablished between two receivers, e.g. a trained receiver havingextensive signal information, and a receiver having less extensiveinformation, to transfer signal information between the receivers sothat either or both has a more complete set of signal information.

Generally speaking, processor 22 compares the radar detector's immediatecoordinates with a stored list of the coordinates of unwanted stationarysources. If the radar detector receives a microwave/laser signal withina certain distance of one of these pre-designated sources, processor 22applies additional constraints to the detection criterion beforealerting the user. Since stationary radar sources make up the bulk ofthe unwanted sources, there is a significant benefit resulting fromthese functions. Further details on these operations are provided belowwith reference to FIGS. 6A through 6D.

FIG. 3 illustrates data structures 50 stored in EEPROM 34 and used formanaging information utilized in accordance with principles of thepresent invention. As seen in FIG. 3, these data structures include aplurality of main entries 52, each including a field 54 for acoordinate, a field 56 for identifying the date and time data wascollected, and three fields 58, 60 and 62 providing information on thesource.

Field 54 provides the coordinate of a “cell” of space. As will beelaborated below, coordinates provided by GPS receiver 32 are reduced inresolution to arrive at a “cell” coordinate, which indicates that thecurrent location of the receiver is within a relatively large (e.g., ⅛or ¼ mile square) block of space on the Earth's surface. This approachreduces the storage requirements for information stored by the radardetector to a manageable level. The sizes of the cells can be variablyadjusted based upon the available memory and the desired precision. Inthe present example, 128 bits are allocated to storing cell coordinates,so the cell coordinates can only have as much precision as can beprovided in 128 bits. a cell, e.g., by discarding the least significantbits of the coordinates. In other applications, different bit sizes andresolutions could be utilized. It will also be noted that the storagerequirements can be reduced by designing the receiver for operation onlyin a specified part of the Earth, e.g., only in Europe, Japan or NorthAmerica. By so doing, part of the coordinates for a cell will not needto be stored because they will be the same for all stored cells. In suchan embodiment, whenever the coordinates provided by the GPS receiverfall outside of the pre-established region, the receiver will eitherdisable all storage of information (if approved via operational inputfrom the user), or establish a new region of interest and discard alldata from previously identified regions. Alternatively, the operator mayset the device in either a “precision” (high coordinate resolution) or“wide area” (low coordinate resolution) mode, based upon the drivinghabits of the driver. In “wide area” mode, the reduced resolution usedfor each cell coordinate permits a greater number of coordinates to bestored, albeit with reduced precision as to each coordinate. Ruraldrivers and others that often follow common paths, would be best suitedto “precision” mode, whereas urban drivers would be better suited to“wide area” mode. As a further alternative, the detector mayautomatically select a mode based upon the memory consumption or thetime lapse before the memory of the detector becomes full; if the memoryfills rapidly, the unit would automatically switch to a “wide area” modeusing low precision coordinates, whereas if the memory never fills orfills only slowly, the unit will remain in its “precision” mode.

The date and time information in field 56 is useful when selecting leastrecently used (oldest) entries in storage for replacement, as isdescribed further below.

Fields 58, 60 and 62 store source incidence counters, one for each of aplurality of frequency blocks. Field 58 stores counter(s) for block(s)in the X band. Field 60 stores counter(s) for block(s) in the K band.Field 62 stores counter(s) for block(s) in the Ka band. The number ofblocks in each band can vary in different embodiments of the presentinvention, and is a function of the signal frequency content detailsprovided by the detector 24 and DSP 26. As one example, the X, K and Kabands are divided into a total of 32 frequency blocks. Each block isprovided a 4-bit counter in fields 58, 60 and 62. The counters have aminimum value of 0 and a maximum value of 15, and are a measure of thenumber of times a signal in the associated frequency block has beendetected at that location. As will be described below in greater detail,the “source incidence” counters are used in identifying geographiclocations that appear to have spurious sources of police radar signals,due to repeated detection of such signals without confirmation of policeactivity.

In the data structures shown in FIG. 3, to save space, main entries 52are interleaved with a greater number of differential entries 64, eachof which stores information for a cell. A first field in a differentialentry 64 is an index pointer 66 to a main entry 52, e.g. an index to astorage location at which the main entry is stored. A second field is adifferential field 68 that identifies the difference between thecoordinate of the differential entry 64 and the coordinate stored in themain entry 52. The index and differential can be stored in substantiallyfewer than 128 bits, so that a differential entry 64 is substantiallysmaller than a main entry, thus saving storage space. Differentialentries further include a date and time field 56 and fields 58, 60 and62 for storing counters for X, K or Ka frequencies, as described above.

FIG. 4 illustrates data structures 70 used to store vehicle motionhistory records or trip records in EEPROM 34. These data structuresinclude main entries 72 which include field 74 storing a 128 bit cellcoordinate, followed by a speed field 76 which can be, for example, 7bits in length. Differential entries 78 associated with each main entryinclude a differential coordinate field 80 indicating the difference inthe cell coordinate from the associated main entry 72, and a speed field76 indicating a speed recorded at the cell. Because motion historyrecords or trip records are stored sequentially during motion of thedetector, differential entries 78 are stored after and adjacent to theassociated main entry 72. Accordingly, differential entries 78 do notrequire an index field to associate the differential entry 78 with amain entry 72, because the association is implied from the location ofthe differential entry 78 in memory after its associated main entry 72.

History entries maybe used for a number of purposes. For example, in thefollowing description, history entries are accessed as part of definingan “everyday route” taken by the detector at the operator'sidentification. History entries may also be used for driver monitoring;they may be downloaded to a host PC via USB interface 46, and evaluatedto determine whether the vehicle has taken abrupt turns, show excessivespeed, or entered undesired locations, all of which may be useful inmonitoring the activity, e.g., of teenage drivers. History entries mayalso be uploaded to PC to provide evidence of the driving history of thevehicle before and at the time of a police citation for speeding. If adriver has been unfairly cited for speeding, history records from thedetector can provide compelling evidence to court that the citation isin error. For the purpose of enabling these uses, history entries storedby fusion processor 22 are encrypted when stored and cannot be modifiedby fusion processor 22 or any PC software supplied for viewing thoseentries.

FIG. 5 illustrates data structures 82 that can be used to store hazardinformation and other flag bits related to cells. These data structures82 include main entries 84 which include a full 128 bit cell coordinatein field 88, followed by a date and time field 90 and flag bits 92indicating the hazard or condition associated with the identifiedlocation. The differential entries 86 include an index field 94 pointingto one of the main entries, a differential coordinate field 96indicating the difference in the cell coordinate from the associatedmain entry 84, a date and time field 98, and a set of flag bits 92indicating the hazard or condition associated with the identifiedlocation. The flag bits may identify various hazard conditions. Forexample, in the specific embodiment described below, there is an “alwayswarn” flag bit that indicates that police activity has previously beenconfirmed at the location, and therefore the user should be warned ofall apparent police radar signals at the location. Further, there is a“location lockout” flag that indicates that broadband sources ofspurious police radar signals have been experienced at the location, andtherefore in the future warnings of police radar signals should besuppressed at the location. Similarly, a “minimal visual lockout” flagindicates that, due to the unwanted distraction of spurious police radarwarnings at a location, only a minimal visual warning should be made ofpolice radar signals identified at the location. The flag bits furtherinclude “frequency lockout” bits, one for each frequency blockidentified by the radar receiver. These bits identify frequencies at thelocation in which spurious police radar signals have previously beenencountered, so that in the future apparent police radar signals at thesame frequencies are ignored. The flag bits may also include additionalflags to warn of other conditions, such as that there was constructionat the identified location, or that some other cause for trafficslowdowns were seen at the identified location, to aid in vehiclenavigation.

The information contained in the databases of FIGS. 3 and 5 may beassimilated by the detector through operation, as is described below.Alternatively, this information may be pre-installed in the detector,e.g. via an upload from a host PC via the USB port 46. There would besubstantial benefits to pre-training a detector in this way for aparticular geographic area. By pre-training the detector, the driverwould not have to enure the audible alerts that would naturally occurbefore it is trained for each source of spurious police radar signals.In a give area, the ideal training profile would not vary much from onedetector to the next, since all detectors should reject the same sourcesin the same areas. As a result, there are few issues that would have tobe resolved in order to transfer training information from one radardetector.

The Internet provides a convenient means for storing and accessingrepositories of information. Web sites will be established and devotedto this task. They will provide several convenient types of traininginformation. One will be a training file containing the coordinateinformation from the online “Speed Trap Registry” at the internet sitewww.speedtrap.com. This information would be usable to set “always warn”bits at the locales of known speed traps. A second type of traininginformation would be training files submitted by individuals for use inparticular areas, and the third type of information would be aggregatetraining files created by integrating individually-submitted informationinto single files organized by region. Aggregate training files would bemanaged and updated by the web site administrator.

Training files would have low value if they could not be readily used byother detectors. The transferability of training files from one detectorto another will depend on the differences in how real world signals areperceived by their embedded processors. In large part, these differencesare a direct result of manufacturing and component variations. Duringthe manufacturing process, a detector goes through a set of calibrationsteps in order to guarantee that the unit meets specifications forSpectral Band Coverage and Sensitivity. These calibration steps reducethe cost of designing the product since lower cost, poorer tolerancecomponents can be used on the assumption that a final manufacturingcalibration procedure will eventually compensate for the lowertolerance. Once calibrated, an acceptable product must also be able toperform over a predefined temperature range.

Component tolerance, manufacturing calibration, and operatingtemperature are key factors that determine how the spectrum of microwavesignals are ‘viewed’ by the embedded Microprocessor or DSP. Radarproducts convert the spectral band such as X-Band into an array ofvalues that are proportional to the signal energy in consecutive slotsor bins of the spectrum. In order for the product to be ‘in tolerance’these slot positions must be adjusted so they precisely cover the fullrange of X, K, and the Ka bands

The calibration procedure is only concerned with guaranteeing that theslots provide adequate coverage of each band. It is less concerned as towhether any one of these slots falls on a precise physical frequency.Therefore the first frequency block in one detector will not necessarybe perceived at the same frequency as the first slot in anotherdetector.

If training data is to be shared between various detectors, it will benecessary for supporting software to compensate for these variations.When new pre-trained data is supplied, the detector will undergo anauthentication procedure in order to determine the relationships betweenthe pre-train data and its own receiver configuration. This will bebased on comparing the frequencies of newly encountered sources to thoseof the pre-train data at matching coordinates. By comparing the observedfrequencies to those in the training set, a “correction profile” will beconstructed, that represents the change between the pre-train data andthe output of the local microwave receiver. At the end of theauthentication procedure, the entire pre-training file will beincorporated into the active train data. During the authenticationprocedure, the user will be exposed to unconditioned detector responses.This authentication procedure will be substantially shorter than thetraining period of a virgin detector. Once authentication is complete,the user will receive a notification indicating that the product isswitching from authentication over to normal operation. If the trainingmode is engaged, the authenticated data will continue to be massaged bynew driving encounters, as detailed below.

Referring now to FIG. 6A, operations of the fusion processor 22 to carryout principles of the present invention can be described in greaterdetail. Fusion processor 22 performs a main loop of steps during regularoperation of GPS enabled radar detection. This main loop of steps isillustrated in FIG. 6A and is detailed in FIGS. 6B through 6F.

When fusion processor 22 is initialized, i.e., when power to the GPSenabled radar detector is turned on, the device is initialized in step100. This initialization step includes performing diagnostic checks onthe various circuitry illustrated in FIG. 2 to insure its properoperation, as well as initialization of the GPS receiver 32 to insureGPS signals can be received accurately by fusion processor 22. Inaddition, various internal variables, such as a variable for identifyinga current position, are initialized. The initial values are chosen toinsure proper operation; for example, the current position variable isinitialized to a value that will cause the first pass through the mainloop FIG. 6A to include processing of a current location in steps 110and 112 in accordance with FIGS. 6B-6E, as discussed below.

The first step in the main loop performed by fusion processor 22, isstep 102, in which radar detection circuitry 24 and 26 is accessed toobtain information on police radar signals currently being received bythe GPS enabled radar detector. In a subsequent step 104, fusionprocessor 22 communicates with GPS receiver 32 to request a currentlocation and a current vehicle speed from the GPS receiver 32. Thisinformation can then be utilized in performing GPS related operationsdescribed in the following steps. As noted above, vehicle speed may alsobe obtained from the vehicle itself via an OBDII interface 44 if thevehicle in which the GPS enabled radar detector is installed has asuitable OBD connector for delivering vehicle speed information. It willbe appreciated further that vehicle location information might also beobtained via an OBDII connector from a GPS receiver that may be builtinto the vehicle within which the GPS enabled radar detector isinstalled. When the vehicle in which the GPS enabled radar detector isinstalled has both vehicle speed and vehicle position informationavailable via an OBDII connector, the GPS receiver 32 may not be used atall, or may not even be included in the GPS enabled radar detector, tofacilitate cost reduction for the GPS enabled radar detector.

Following steps 102 and 104 in which current police radar and GPSrelated information is obtained, different actions are taken based uponwhether GPS information is available. Specifically, in step 106 it isdetermined whether a GPS signal has been received. If a GPS signal isavailable, then all GPS enhanced functions of the radar detector may beperformed. If no GPS signal has been received, then the radar detectorwill revert to processing police radar signals at a manner analogous toconventional non-GPS enabled radar detectors.

Assuming for the moment that a GPS signal is available in step 106, andtherefore a current position for the vehicle is known, then in step 108a sequence of steps is preformed to process the GPS signal, as isfurther detailed below with reference to FIG. 6B, 6C and 6D. Thisprocessing can include retrieval and/or updating of stored police radarinformation and the signal information database illustrated in FIG. 3,the vehicle history database illustrated in FIG. 4, and/or the flagdatabase illustrated in FIG. 5.

After processing the GPS signal, in step 110 keypad activity on keypad36 is detected and processed to alter operating modes of the GPS enabledradar detector, as described below in further detail with reference toFIG. 6E. The operative modes controllable through the keypad include:

-   -   a “warning suppression” mode in which warnings, particularly        audible warnings, produced by the GPS enabled radar detector are        suppressed so that they are not disturbing to the operator of        the vehicle.    -   an “expert meter” mode in which detailed information regarding        received warning signals are displayed on display 38 of the GPS        enabled radar detector, as described in U.S. Pat. No. 5,668,554,        which is hereby incorporated by reference herein in its        entirety.    -   a “data overwrite” mode in which the GPS enabled radar detector        saves, into the signal information database of FIG. 3, data        regarding any location not previously stored in the database,        even when this signal information database is full, by        overwriting the oldest data in the signal information database        when necessary. When the “data overwrite” mode is disabled, then        the signal information database will not be overwritten once it        becomes full.    -   a “frequency lockout” mode, in which police radar frequencies        detected by the receiver are taken to be from non-police        sources, and appropriate flags are set in the flag database        illustrated in FIG. 5. The “frequency lockout” mode is engaged        by the vehicle operator when non-police radar signals are being        received and the operator wishes to suppress future warning        signals caused by the same sources at the same geographic        locations. As noted below, “frequency lockout” mode can only be        engaged while the GPS enabled radar detector is detecting an        apparent police radar signal and will be automatically        disengaged when this signal is no longer being received.    -   a “location lockout” mode, in which the flag database of FIG. 5        is updated to suppress all audible warnings of radar signals at        the current location of the vehicle. As is the case with the        “frequency lockout” mode, the “location lockout” mode will be        enabled by a vehicle operator when the vehicle is near to a        known source of spurious police radar signals of a broadband        character. The “location lockout” mode can only be engaged while        the GPS enabled radar detector is detecting an apparent police        radar signal, and will be automatically disengaged whenever a        police radar signal is no longer being received from the GPS        enabled radar detector.    -   a “minimal visual lockout” mode, in which the flag database of        FIG. 5 is updated to suppress most or all visual warnings of        radar signals at the current location of the vehicle. The        “location lockout” mode will be enabled by a vehicle operator        when the vehicle is near to a known source of spurious police        radar signals of a broadband character, and at that location        does not wish to be disturbed by even a visual radar signal        warning. The “location lockout” mode can only be engaged while        the GPS enabled radar detector is detecting an apparent police        radar signal, and will be automatically disengaged whenever a        police radar signal is no longer being received from the GPS        enabled radar detector.    -   a “police confirmation” mode, in which flags in the flag        database of FIG. 5 will be set to insure a warning signal is        always delivered for any police radar signal received at the        current vehicle location. The “police confirmation” mode will be        activated by a vehicle operator upon sighting a police stakeout.    -   a “training” mode, in which the GPS enabled radar detector will        store signal information for all geographic locations that the        GPS enabled radar detector reaches or passes during operation.        When “training” mode is disabled, the signal incidence counters        found in the signal information database of FIG. 3, will not be        modified by the GPS enabled radar detector during its normal        operation.    -   a “route identification” mode in which the route currently        traveled by the vehicle is memorized by the GPS enabled radar        detector to be subsequently referenced in performing radar        detection. Using “route identification” mode, a user may        establish one or more everyday routes traveled by the vehicle,        and cause the GPS enabled radar detector to continuously update        its signal incidence information in the signal information        database of FIG. 3 whenever one of these routes are traversed.        Routes are identified by an operator by entering the “route        identification” mode at the beginning a route, and then exiting        the “route identification” at the end of the route.

After selecting appropriate modes based upon keypad activity, in step112, an appropriate audible or visible response is produced by the GPSenabled radar detector based upon it current operating mode and thepresence or absence of radar detector signal received in step 102.Details of this operation are described below with reference to FIG. 6F.After step 112, processing returns to step 102 to obtain a new radardetector signal output and a new current location and speed and thenperform additional analysis of that data as described above.

As noted above, in some circumstances a GPS signal will not be availableduring operation of the GPS enabled radar detector. In this case,processing continues from step 106 to step 114 in which any non-GPSrelated operational modes may be activated based upon the activity atkeypad 35. GPS enabled modes are unavailable so long as no GPS signalhas been obtained, so the processing in step 114 eliminates those modeswhich cannot be activated in the absence of a GPS signal. After step114, processing continues to step 112 in which an appropriate audible orvisible response is generated based upon the current operating mode andthe radar detected signal received in step 102.

Referring now to FIG. 6B, the processing performed on a GPS signal instep 108 of FIG. 6A can be described in greater detail. As a first step120, GPS coordinates received from the GPS receiver 32 are modified byreducing their accuracy. This process is known as “gridding” thecoordinates and involves truncating that part of the coordinate ofgreater accuracy than the defined grid. As a consequence of thismodification, the GPS coordinate is mapped into a cell number; everylocation on the globe falls within a cell of the grid, and has aparticular cell number derived from the most significant bits of the GPScoordinates measured within the cell. Cells may be relatively small,i.e., one-eighth of a mile square, or maybe relatively large, i.e., onemile square.

After a current cell number is generated from GPS coordinates, thenactions are taken based upon whether the vehicle is transitioning fromone cell to another, and further based upon current operational modes ofthe GPS enabled grid are detected. In the first of these steps 122, itis determined whether the current cell obtained from the GPS receiver isthe same a stored prior cell obtained from the GPS receiver during theprevious pass through the processing of FIG. 6B. If so, the vehicle isin the same cell as has been previously processed, and then no furtherprocessing for the current cell is required, and the process of FIG. 6Breturns.

If, however, the vehicle has moved to a new cell, then in step 124, thecell number for this new current cell is stored as the prior cell, sothat in subsequent passes through the process of FIG. 6B, it will beknown whether or not the vehicle has moved to another cell.

After step 124, steps are taken to manage “everyday route” modes of theGPS enabled radar detector. As noted above, the user of the GPS enabledradar detector may establish one or more everyday routes traveled by thevehicle and cause the GPS enabled radar detector to, along those routes,continuously update its signal incidence information in the signalinformation database of FIG. 3. Accordingly, when the GPS enabled radardetector detects that it is following one of these everyday routes, thenit will automatically enter its everyday route mode, and subsequentlyperform different processing (as further described below in connectionwith FIGS. 6C and 6D). As seen in FIG. 6B, each time the GPS enabledradar detector determines in step 122 that it has passed from one cellto another, then (a.) if the detector has been following an everydayroute, an evaluation is made whether the GPS enabled radar detector iscontinuing to follow the previously defined everyday route, or (b.) ifthe detector has not been following an everyday route, a determinationis made whether the GPS enabled radar detector has started following apreviously defined everyday route.

In the first step of this process, in step 126 it is determined whetherthe GPS enabled radar detector is already in its “everyday route” mode.If the radar detector is not currently not in its “everyday route” mode,then it is determined whether the radar detector is entering an everydayroute; specifically, in step 128, it is determined whether the currentcell coordinate is on any of the pre-stored everyday routes. If thecurrent cell is on one of the everyday routes, then the GPS enabledradar detector will determine that the vehicle carrying the detector isbeginning or joining one of these pre-stored routes. In such a case, instep 130 the GPS enabled radar detector will enter its “everyday route”mode for the stored route containing the current cell coordinate. If thecurrent coordinate is not on any stored route, step 130 is bypassed.

Returning to step 126, if the GPS enabled radar detector is already inits “everyday route” mode, then it is determined whether the detector iscontinuing to follow this route. In this case, processing proceeds fromstep 126 to step 132 to determine whether the everyday route is beingfollowed. Specifically, in step 132 it is determined whether the currentcoordinate is on the current everyday route. If not, then in step 134the GPS enabled radar detector exits it “everyday route” mode,indicating that the vehicle is no longer on the previously storedeveryday route. Otherwise, step 134 is bypassed, and the detectorremains in its “everyday route” mode.

Following step 134 or immediately following step 130, additional stepsare performed to determine whether and how to update previously storedsignal incidence information in the signal information database of FIG.3. Processing also proceeds to step 140 from steps 132 or directly fromstep 128 based upon conditions described above.

In step 140 it is determined whether a radar signal is being received bythe GPS enabled radar detector. If so, then in step 142 the proceduredescribed below with reference to FIG. 6C is performed to update, asneeded, the signal information database of FIG. 3. If no radar signal isbeing currently detected, then in step 144 the process described belowwith reference to FIG. 6D is performed to update, as needed, the signalinformation database of FIG. 3. After step 142 or 144, in step 146 thehistory database of FIG. 4 is updated by removing the oldest historyentry from that database (if necessary to make room), and creating a newhistory entry for the current cell. The new history entry will includethe cell coordinate or a differential coordinate as discussed above withreference to FIG. 4, and would also include a vehicle speed as obtainedin step 104 from the GPS receiver or alternatively from an OBD IIinterface to the vehicle. Following step 146, the processing of the GPSsignal is complete.

Referring to FIG. 6C, updating of the signal information database ofFIG. 3 in the presence of a police radar signal can be elaborated. Inthe first step 150 it is determined whether the GPS enabled radardetector is in its “signal tracking” mode. The “signal tracking” mode isentered whenever the GPS enabled radar detector is receiving an apparentpolice radar signal as the detector is passing through space. So long asan apparent police radar signal is being continuously detected, thedetector will remain in signal tracking mode in order to associate thatpolice radar signal with all of the geographic locations in which it wasdetected. It will be appreciated that the process of FIG. 6C will notcommence unless there is a police radar signal being detected;therefore, the first step 150 is to determine whether the detector is inits signal tracking mode, and if not, in step 152 to enter the signaltracking mode to thereby begin tracking the police radar signal that hadnot previously been detected.

After step 152 or after step 150 if the detector is already in itssignal tracking mode, in step 154 the current cell coordinate and thefrequency data for the current cell is stored in a special trackingstorage area accessible to fusion processor 22 in EEPROM 34. Thefrequency data and cell information stored in this tracking storage canbe used subsequently to identify the source of the tracked police radarsignal more accurately.

After step 154, different actions are taken based upon whether thesignal information database of FIG. 3 already contains signalinformation for the detector's current cell coordinate. If there is nomatching cells in the signal information database of FIG. 3, thenprocessing continues to step 158 in which it is determined whether thesignal information database of FIG. 3 is full, i.e., all the storagespace allocated to this database in EEPROM 34 has been consumed. If allthe space has been consumed, then in step 160 it is determined whetherthe GPS enabled radar detector is in its “data overwrite” mode. If so,then the user has identified that current information should be storedfor each cell encountered by the vehicle, even when doing so requiresthe elimination of older stored data. Accordingly, in data overwritemode, processing proceeds from step 160 to step 162 in which the oldestsignal and flag entries in the databases of FIGS. 3 and 5 are removed,and then to step 164 in which new signal and flag entries are createdfor the current cell so that signal information and flag information canbe stored. If, however, the detector is not in its “data overwrite” modein step 160, then a warning is delivered to the user that storage ofinformation is being prevented due to the database being full (step166).

After step 166 or 164, or immediately after step 156 if there is alreadydata stored for the current cell, in step 168 it is determined whetherthe GPS enabled radar detector is in its “training” or “everyday route”mode. As noted above, in these modes, signal information stored in thedatabase of FIG. 3 is continuously updated each time a cell isencountered. Accordingly, if the detector is in either its “training” or“everyday route” mode, then in step 170 the unwanted source incidencecounter for each frequency block identified by the radar receiver 24 ascontaining signal, is incremented, preventing an overflow. Subsequently,in step 172 the unwanted source incidence counter for each frequencyblock identified by the radar receiver 24 as not having signal, isdecremented, preventing an underflow. This thus updates the sourceincidence counters for each frequency block for the current cell. Afterthis processing, or immediately after step 168 if the GPS enabled radardetector is not in the “training” or “everyday route” mode, updating instep 142 is complete.

Referring now to FIG. 6D, processing in step 144, to update variousdatabases when no signal is detected, can be explained. As will beelaborated below, when no police radar signal is being received by theGPS enabled radar detector, this indicates that many of the modesdescribed above for tracking and identifying sources of police radarsignal should be terminated.

Specifically, in step 180 it is determined whether the GPS enabled radardetector is in “signal tracking” mode. As discussed above, the “signaltracking” mode signifies that the GPS enabled radar detector iscurrently tracking the cell locations and frequencies of an apparentpolice radar signal detected by the GPS enabled radar detector. Asdiscussed above with reference to FIG. 6C, step 152, the GPS enabledradar detector will enter “signal tracking” whenever an apparent policeradar signal is received. So long as the signal is continuouslyreceived, processing of the GPS signal will pass through step 140 ofFIG. 6B to FIG. 6C, and “signal tracking” mode will remain engaged. If,however, no police radar signal is being received when processing of theGPS signal passes through step 140 of FIG. 6B, then processing will passto FIG. 6D and thus to step 180 of FIG. 6D. In the first pass throughFIG. 6B after a police radar signal has faded, e.g., due to motion ofthe vehicle past the source of that signal, “signal tracking” mode willstill be engaged as a consequence of prior passes through FIGS. 6B and6C. Thus, if in step 180 of FIG. 6D, if “signal tracking” mode isengaged, but no police radar signal is currently being received, thisindicates that the previously detected signal has just faded. In such asituation, a complete record has been made of the locations in which thesource was received by the GPS enabled radar detector. This record canbe used to characterize the source as to location and frequency, byanalyzing the cells in which the signal was tracked, and the frequenciesin which the signal was tracked. Thus, if in step 144, the GPS enabledradar detector is “signal tracking” mode, in step 182 the detector exitsits “signal tracking” mode. Subsequently, steps are taken to storerelevant information collected for the tracked signal.

In a first step 184, it is determined whether the GPS enabled radardetector is in “police confirmation” mode. If so, then the vehicleoperator has pressed a key on the keypad of the GPS enabled radardetector indicating that a police stakeout was sighted, during thetracking of apparent police radar signals. In such a case, in step 186the “always warn” flag bit is set for all or the central most cells inthe tracked sequence of cells identified while in “signal tracking”mode. Thus, the likely locations of the source of the tracked signal areidentified and the flag bits are set so that any apparent police radarsignal found in those cells will always cause the user to be warned ofpolice radar.

If the GPS enabled radar detector is not in “police confirmation” mode,in step 188 it is determined whether the GPS enabled radar detector isin “frequency lockout” mode. As described above, the detector will be in“frequency lockout” mode if the vehicle operator has used the keypad toindicate that any apparent police radar signals that were tracked in thepreceding and current cell, are from spurious sources, and that thefrequencies in which those spurious signals appeared should be ignoredin subsequent passes through the same cell location. Accordingly, if thedetector is in “frequency lockout” mode in step 188, processingcontinues to step 190 in which the lockout bits, in the flag bits 92,are set for all or central cells of the tracked path taken by thevehicle, for those frequencies that were identified during the “signaltracking” mode.

After step 190, or immediately after step 188 if the detector is not in“frequency lockout” mode, it is determined whether the receiver is in“location lockout” mode in step 192. It is noted above, “locationlockout” mode is engaged by the vehicle operator when broadband sourcesof spurious produced radar signals are experienced at a geographiclocation, and the operator wishes to lockout all frequencies at thatlocation. In such a case, in step 194 all of the frequency lockout bitsfor all or the central most cells in the tracked path of the vehicle areset.

After step 194, or immediately after step 192 if the detector is not in“location lockout” mode, in step 196 it is determined whether thedetector is in “minimal visual” mode. As noted below, the detector willbe placed in “minimal visual” mode by the operator when the operatorwishes to minimize the indications of police radar signals produced whenpassing through a geographic region. In such a case, processingcontinues from step 196 to step 198 in which a minimal visual (MV) flagbit is set in the flag database of FIG. 5 for all or the central mostcells in the tracked path of the vehicle.

After step 198, or immediately after step 196 if the detector is not in“minimal visual” mode, or immediately after step 186 if the GPS enabledradar detector is in “police confirmation” mode, in step 200 it isdetermined whether the signal information database of FIG. 3 includesdata for matching or neighboring cells to those cells in the trackedpath of the vehicle. If such a match is found, then in step 202 it isdetermined whether the detector is in its “training” or “everyday route”mode. If so, then the detector should update the stored signalinformation for the current cell. Specifically, to update signalinformation, in step 204 all of the unwanted source incidence countersfor frequency blocks identified by the receiver are decremented,preventing underflow.

Following step 204, or immediately following step 200 if there is nomatching signal information or step 202 if the detector is not in its“training” or “everyday route” mode, in step 206 the “frequencylockout”, “location lockout”, “minimal visual” and “police confirmation”modes are cleared, because the tracking of a police radar signal hasended, and these modes are therefore no longer relevant to the currentlocation of the vehicle.

Referring now to FIG. 6E, the processing of keypad activity to enter andexit the various modes described throughout can be explained. As notedwith reference to FIG. 6A, various modes are available only if a GPSsignal has been obtained from the GPS receiver. If a GPS signal has beenobtained then modes are selected from the keypad beginning at step 110.If a GPS signal has not been obtained then modes are selected from thekeypad beginning at step 114, and a substantial number of modes aredisabled and cannot be selected in this circumstance.

The keypad activity to select and deselect a mode may vary based uponthe application and style of the GPS enabled radar detector. The displayand keypad 38 and 36 may interact to produce a menu system for selectingparticular modes and displaying associated information. Alternatively,individual keys of keypad 36 maybe utilized to directly activate certainmodes. Furthermore, display 3 8 may include icons or other indicators toidentify currently activated modes.

A first collection of modes that may be activated via the keypad 36, arethe “frequency lockout”, “location lockout”, and “minimal visuallockout” modes. Through interactions with the keypad in step 210, theuser may initiate or terminate these modes. As described above, wheninitiated, these modes cause lockout information to be stored into flagsof the flag database of FIG. 5 upon termination of tracking an apparentpolice radar signal. If these modes are not engaged at the time that thepolice radar signal fades from reception, then no action will be takento set lockout bits in the flag database of FIG. 5. This approachpermits a vehicle operator to initiate a lockout mode and then cancelthe lockout mode, for example if the operator initially believes a radarsignal to be spurious, but then determines that it is in fact beinggenerated by a police source. It will also be noted that, by theoperations of FIG. 6D, the “police confirmation” mode will override the“lockout” modes, in that if the “police confirmation” mode is engagedwhen a police radar signal fades from reception, any “lockout” modesthat are engaged will be ignored. The user is not, however, preventedfrom engaging both modes simultaneously. For example, the user mayreceive a signal believed to be spurious, and engage a “lockout” mode.The user may then sight a police vehicle and, believing the signal isnot spurious, engage “police confirmation” mode. The user may later,however, confirm that the police vehicle is not engaged in a speed trap,and consequently disengage “police confirmation” mode. If the receivedsignal then fades from view, the “lockout” mode will be active andaccordingly lockout bits will be set as described above with referenceto FIG. 6D.

In step 212 the vehicle operator may enter or exit the “training mode”,which as described above causes the GPS enabled radar detector tocollect signal information for all cells that the vehicle traverses.

A third activity that may be undertaken with the keypad, in step 214, isto request to clear all lockouts for the current vehicle location. Thisstep may be taken where the GPS enabled radar detector has previouslybeen programmed to lockout a frequency or location and subsequently thevehicle operator sights a police source at that location, and wishes toterminate the lockout at that location. When the vehicle operatorrequests to clear all existing lockouts, in step 216 the gridcoordinates of the vehicle location are compared to all existing membersof the flag database of FIG. 5, and all matching and/or neighboringcells are selected and all lockout bits in those cells are cleared.

The vehicle operator may also enter or exit a “warning suppression” modein step 218, in which a warning for a currently tracked police radarsignal is suppressed, i.e., so that the detector does not continue toissue warning signals for the same radar signal received. An operatormay also enter or exit an “expert meter” mode in step 220, requestingthat enhanced information on police radar signals received and/or GPSrelated lockout information or signal incidence information be displayedon display 38 of the detector. An operator may also enter a “dataoverride” mode in step 222, thus requesting that signal information fornew locations visited by the vehicle not found in the database bestored, even at the expense of overriding the oldest previously storeddata of this kind. It is also possible, as shown in FIG. 6E, that theremay be no keypad activity at the time that operation of the detectorpasses through step 110. In this circumstance, step 224, no furtherprocessing is performed.

A further action that a vehicle operator may take is to confirm of apolice sighting in step 226. This step causes the detector to enter“police confirmation” mode, so that the detector will ensure that policeradar signals at the identified stakeout location is handled withparticular urgency. Accordingly, when the user enters a policeconfirmation in step 226, then action is taken to set one for more“always warn” flag bits of the flag database of FIG. 5.

If at the time that the operator presses the police confirmation, noapparent police radar signal is currently being tracked, then in step228 the receiver will not be in “signal tracking” mode. In such acircumstance, processing will continue from step 228 to step 232 inwhich the “always warn” flag bit is set for the current and neighboringcells of the current location of the vehicle. This step ensures that infuture times when a police radar signal is detected in these locations,a warning will be delivered to the vehicle operator regardless of otherconditions applicable at the time. If a signal is being tracked at thetime that the vehicle operator enters a police confirmation, then aslightly different activity is undertaken. Specifically, in this caseprocessing continues from step 228 to step 230 in which the “policeconfirmation” mode is entered. As noted above with respect to FIG. 6D,once the receiver is in police confirmation mode, upon termination ofsignal tracking, central or all cells along the tracked path of thevehicle when the police radar signal was detected, will be marked as“always warn” in the flag database of FIG. 5.

A further activity that may be undertaken by a vehicle operator is toindicate e that the vehicle is at the beginning of an everyday route, instep 240. Doing so causes the GPS enabled radar detector to begin tocollect information on the everyday route, for the purpose of ultimatelystoring a definition of an everyday route to be evaluated in connectionwith the processing described in connection with FIG. 6B, step 128. Whenthe user indicates that the vehicle is at the beginning of an everydayroute, in step 242 the current cell coordinate and the current entry inthe vehicle history database of FIG. 4 are stored for later reference.Then in step 244 the detector enters a “route identification” mode, usedlater in establishing that a route has been identified and is beingtracked. When the user wishes to complete an everyday route or wishes toclear everyday route processing for the current vehicle location, theuser engages an end or clear operation in step 246. When this step istaken by the user, an initial determination is made in step 248 whetherthe detector is currently in its “route identification” mode. If so,then the user has identified the end of the everyday route that waspreviously identified in step 240. Thus, in step 250 it is determinedwhether the history entry identified and marked in step 242 continues tostore the location of the route start that was stored in step 242. Ifso, then all of the cells accumulated in the vehicle history followingthe history entry identified in step 242, describe the route taken bythe vehicle along the path selected by the user. In this case, all cellsaccumulated in the history database of FIG. 4 are copied to a special“everyday route” storage area so that all of these cells are availablefor analysis in connection with the processing of FIG. 6B, step 128.After storing the accumulated history entry cells, in step 252,processing is completed. After step 252, in step 253 the “routeidentification” mode is exited.

If in step 250, it is determined that the vehicle history database ofFIG. 4 is no longer storing the start of the everyday route defined bythe user, then the everyday route defined by the user was too lengthy tobe processed by the GPS enabled radar detector. In such a situation, instep 254 the stored route start information is cleared and the “routeidentification” mode is exited.

If in step 248, the GPS enabled radar detector is not in “routeidentification” mode at the time that the vehicle operator requests theend of everyday route in step 246, then the vehicle operator may wish todelete any everyday route that includes or passes through the currentcell. Thus, in step 258, a display is generated to the operatorrequesting confirmation that any everyday route including the currentcell should be cleared. If a confirmation is received in step 258, thenin step 260 all everyday routes including the current cell are erasedfrom the everyday route storage of the GPS enabled radar detector. Ifthe vehicle operator does not confirm erasure of everyday routeinformation, then processing completes without erasing any everydayroute information.

In step 114 of FIG. 6A, non GPS modes of the GPS enabled radar detectormay be activated utilizing keypad activity. This step may be taken if noGPS signal is available at some point during operation of the GPSenabled radar detector. In such a circumstance, in step 262 all GPSrelated modes of the GPS enabled radar detector are cleared. Theseinclude the frequency location and minimal visual lockout modes, theroute identification mode, the police confirmation mode, the trainingmode and the everyday route mode (step 262). After clearing these modes,non GPS related modes of the GPS enabled radar detector can beinitiated. These modes include the “warning suppression” mode (step218), the “expert meter” (step 220), and the “data override” mode (step222). Other modes that the operator may attempt to select will beignored so long as no GPS signal is being received.

Referring now to FIG. 6F, operations performed in connection withgenerating audible and visible responses to police radar signals can beexplained. In a first step 270, it is determined whether any of a numberof lockout or other flags in the flag database of FIG. 5 are applicableto the current cell. In this step 270, the flag database is evaluated tosee if there is an entry for the current cell, and if so whether thelocation lockout, minimal visual lockout or always warn flags in thatentry are set. If none of these flags are set, then processing of policeradar signals at the current location proceeds based upon information inthe signal information database of FIG. 3, or based upon defaults ifthere is no previously stored information. Accordingly, if none of theflags identified in step 270 are set, then in step 272 it is determinedwhether there is a cell match in the signal information database of FIG.3. If there is such a cell match, the frequencies identified by theradar receiver are compared to the signal information in the entry inthe database of FIG. 3.

In the first step of this process, the first frequency block identifiedby the receiver is selected (step 274). Then, in step 276, it isdetermined whether the selected frequency block in the signalinformation database has a source incidence counter greater than apredetermined “ignore” threshold. If radar signals have been frequentlydetected in the selected frequency block, but there has never been apolice sighting there (and thus the “always warn” flag has never beenset), this is strongly indicative of a false source at that location.Accordingly, if the source incidence counter for a frequency blockexceeds the “ignore” threshold, then any police radar signals identifiedin that frequency block are ignored. If, however, the selected frequencyblock does not have a source incidence counter greater than thisthreshold, then in step 278 it is determined whether the frequency blockhas a lockout flag bit set in the flag database of FIG. 5. Only if thefrequency lockout bit for the selected frequency is not set, willprocessing continue to step 280. In step 280 it is determined whetherthe selected frequency block has a source incidence counter greater thana “silent” threshold. If the source incidence counter exceeds thisthreshold, then it is likely that there is a false source radar signalsat the location, and as a result in step 282 a visual-only response isgenerated for the frequency band including the selected frequency block.If, however, the selected frequency block does not have a sourceincidence counter greater than the silent threshold, then an audible andvisual response can be generated. In step 284 it is determined whetherthe receiver is in “warning suppression” mode. If not in this mode, thenan audible and visual response is generated for the band of signalsincluding the selected frequency block. Visual response may be a normalresponse or may be an “expert meter” response depending upon the statusof the “expert meter” mode of the receiver.

After steps 282 or 284, or immediately after steps 276 or 278 if afrequency block is to be ignored or has been locked out, in step 285 itis determined whether there are additional frequency blocks to beevaluated. If so, then in step 286 the next frequency block is selectedand processing returns to step 276. After all frequency blocks have beenevaluated, processing ends at step 285, and the generation of audibleand visual responses is completed.

Returning to step 270, if one of the location lockout, minimal visuallockout or always warn flags are set for the current cell, then in step290 and in step 292 it is determined which of these flags is set. If the“always warn” flag is set for the current cell, then in step 288 anaudible and visual response is generated for all frequencies identifiedby the received, unless suppressed by “warning suppression mode”. Step288 is also performed following step 272 if there is no match for thecurrent cell in the signal information database.

If the “minimal visual” flag is set for a current cell, but the “alwayswarn” flag is not, processing proceeds from step 290 to step 292 andthen to step 294 in which a minimal visual response is generated for allfrequencies identified by the receiver, such as a small blinking flag onthe display of the detector.

If the “always warn” and “minimal visual” flags are not set, but the“location lockout” flag is set for the current cell, then processingcontinues from step 270 through steps 290 and 292 to step 296, in whicha visual-only response is generated for all frequencies identified bythe receiver, which may include expert meter information or otherdetails available from the detector.

After step 288, 294 or 296 processing to generate an audible and/orvisual response is completed.

While the present invention has been illustrated by a description ofvarious embodiments and while these embodiments have been described inconsiderable detail, it is not the intention of the applicants torestrict or in any way limit the scope of the appended claims to suchdetail. Additional advantages and modifications will readily appear tothose skilled in the art.

For example, it will be appreciated that principles of the presentinvention may also be applied to systems that do not include a GPSreceiver. For example, in a simplified embodiment of the presentinvention, the radar warning receiver may automatically enter its“warning suppression” mode based upon the speed of the vehicle. Thespeed of the vehicle may, of course, be obtained from a GPS receiver,but if a GPS receiver is not available and/or unnecessarily expensive toinclude in the receiver, the receiver could obtain vehicle speedinformation directly from the vehicle's on-board information processingsystem via the ODB II interface discussed above. A threshold speed of 15MPH could be used as a default, with “warning suppression” modeautomatically engaged at speeds below this threshold. This threshold maybe user-adjustable, e.g., within a range such as 5 to 50 MPH.

The interface connector used by the receiver may take other forms thanthe known USB standard. It may use any computer interface standard(e.g., IEEE 488), or an automotive wiring standard, the J1854, CAN, BH12and LIN standards, or others.

In a more refined embodiment, a “everyday route” mode could be included,in which the operator can perform “everyday route velocity” training. Inthis “everyday route velocity” training mode, the vehicle speed at eachpoint along the “everyday route” would be stored along with the celllocations along the route. Subsequently, when the detector determinesthat it is on a previously defined everyday route, it will enter“warning suppression” mode whenever the vehicle speed is within atolerance of, or below, the velocity recorded when in “everyday routevelocity” training mode. Thus, no warning signals will be generated solong as the vehicle is not traveling faster than the threshold speedidentified by the operator during “everyday route velocity” training ofthe detector.

It will be further appreciated that the “signal tracking” mode describedherein may operate upon each frequency band independently, so that the“signal tracking” mode maybe engaged for one band while disengaged forothers, and so that the fade-out of a tracked signal at one frequencywill cause flag bits to be set for that frequency while otherfrequencies continue to be tracked.

It will be further appreciated that the determination of whether togenerate an audible or visual response, or both, may be based oninformation in addition to the flags applicable to the current cell ofthe vehicle. For example, the flags in cells recently traversed by thevehicle may also be consulted to determine whether audible or visualsignals should be suppressed at a current cell. Thus, for example, ifthe detector passes through a cell that has been marked for “minimalvisual” lockout, warnings will be suppressed for subsequent cellsentered by the vehicle while the same signal is being tracked,regardless of whether flag bits in those cells call for a lockout.

The invention in its broader aspects is therefore not limited to thespecific details, representative apparatus and method, and illustrativeexample shown and described. Accordingly, departures may be made fromsuch details without departing from the spirit or scope of applicant'sgeneral inventive concept.

1. A police activity transponder comprising: a receiver sectionreceiving signals generated in the context of law enforcement activity,and a warning section responding to the receiver section and providing awarning if a received signal correlates to a law enforcement signal, thewarning produced in response to a law enforcement signal varying inrelation to vehicle speed data; the transponder being responsive tovehicle speed data derived from a position determining circuit.
 2. Thepolice activity transponder of claim 1 wherein the receiver sectionreceives electromagnetic radar signals in a radar band.
 3. The policeactivity transponder of claim 1 wherein the receiver section receivessignals carried in the visible or infrared spectrum.
 4. The policeactivity transponder of claim 1 further comprising an interface readingvehicle speed data from a host vehicle.
 5. The police activitytransponder of claim 4 wherein the interface is an OBDII compliantinterface.
 6. The police activity transponder of claim 4 wherein theinterface is an IVBD compliant interface.
 7. The police activitytransponder of claim 1 further comprising an interface reading thevehicle speed data from a position determining circuit in a hostvehicle.
 8. The police activity transponder of claim 7 wherein theinterface is an OBDII compliant interface.
 9. The police activitytransponder of claim 7 wherein the interface is an IVBD compliantinterface.
 10. The police activity transponder of claim 1 wherein thewarning section is a visible display that makes visible warnings. 11.The police activity transponder of claim 1 wherein the warning sectionis an audio speaker that makes audible warnings.
 12. The police activitytransponder of claim 1 further comprising a position determiningcircuit.
 13. A police activity transponder comprising: a receiversection receiving signals generated in the context of law enforcementactivity; and a warning section responding to the receiver section andproviding a warning if a received signal correlates to a law enforcementsignal, the warning delivered by the warning section being suppressed inrelation to vehicle speed data; the transponder being responsive tovehicle speed data derived from a position determining circuit.
 14. Thepolice activity transponder of claim 13 wherein the receiver sectionreceives electromagnetic radar signals in a radar band.
 15. The policeactivity transponder of claim 13 wherein the receiver section receivessignals carried in the visible or infrared spectrum.
 16. The policeactivity transponder of claim 13 further comprising an interface readingvehicle speed data from a host vehicle.
 17. The police activitytransponder of claim 16 wherein the interface is an OBDII compliantinterface.
 18. The police activity transponder of claim 16 wherein theinterface is an IVBD compliant interface.
 19. The police activitytransponder of claim 13 further comprising an interface reading thevehicle speed data from a position determining circuit in a hostvehicle.
 20. The police activity transponder of claim 19 wherein theinterface is an OBDII compliant interface.
 21. The police activitytransponder of claim 19 wherein the interface is an IVBD compliantinterface.
 22. The police activity transponder of claim 13 wherein thewarning section is a visible display that makes visible warnings. 23.The police activity transponder of claim 13 wherein the warning sectionis an audio speaker that makes audible warnings.
 24. The police activitytransponder of claim 13 further comprising a position determiningcircuit.
 25. A police warning receiver comprising: a receiver sectionadapted to receive electromagnetic signals indicative of policeactivity; an alert section responsive to the receiver section andadapted to provide an alert if a received electromagnetic signalcorrelates to a police signal; a display for displaying information to auser; a position determining circuit generating a location signal; andstorage for information regarding rejectable electromagnetic signals notrelated to police activity at specific geographic locations, whereininformation presented on said display includes information relating torejectable electromagnetic signals.
 26. The police warning receiver ofclaim 25, wherein said electromagnetic signals include radar signals ina radar band.
 27. The police warning receiver of claim 25, wherein saidelectromagnetic signals are carried in the visible or infrared spectrum.28. The police warning receiver of claim 25, wherein the alert sectioncorrelates information relating to a prior encounter of a rejectableelectromagnetic signal to said received electromagnetic signal, andalters the alert based upon the result of the correlation.
 29. Thepolice warning receiver of claim 25 wherein said information relating torejectable electromagnetic signals comprises signal informationidentifying signals received at each geographic location.
 30. The policewarning receiver of claim 29 wherein said signal information includes asignal incidence counter identifying a number of times a signal has beenreceived by said receiver at each geographic location.
 31. The policewarning receiver of claim 25 wherein said information relating torejectable electromagnetic signals comprises flags associated withgeographic locations, said flags identifying rejectable signals at eachgeographic location.
 32. The police warning receiver of claim 25 furthercomprising an interface connector, wherein information relating torejectable electromagnetic signals is stored in said storage via saidinterface connector.
 33. The police warning receiver of claim 32 whereinsaid interface connector complies with one of a universal serial busstandard, an automotive wiring standard, the J1862, CAN, BH12 and LINstandards.
 34. The police warning receiver of claim 25 adapted to accessand store said information relating to prior encounters from externalsources.
 35. The police warning receiver of claim 34 further comprisingcommunication circuitry for obtaining said signal information from anInternet resource.
 36. The police warning receiver of claim 34 furthercomprising communication circuitry for obtaining said signal informationfrom a general purpose computer.
 37. The police warning receiver ofclaim 34 further comprising communication circuitry for obtaining saidsignal information from another police warning receiver.
 38. A policewarning receiver comprising: a receiver section adapted to receiveelectromagnetic signals indicative of police activity; an alert sectionresponsive to the receiver section and adapted to provide an alert if areceived electromagnetic signal correlates to a police signal; aposition determining circuit generating a location signal; and storagefor information regarding specific geographic locations.
 39. The policewarning receiver of claim 38, wherein said electromagnetic signalsinclude radar signals in a radar band.
 40. The police warning receiverof claim 38, wherein said electromagnetic signals are carried in thevisible or infrared spectrum.
 41. The police warning receiver of claim 38, wherein the alert section correlates information relating to a priorencounter of a rejectable electromagnetic signal at a specificgeographic location to said received electromagnetic signal, and altersthe alert based upon the result of the correlation.
 42. The policewarning receiver of claim 38 wherein said information relating torejectable electromagnetic signals comprises signal informationidentifying signals received at each geographic location.
 43. The policewarning receiver of claim 42 wherein said signal information includes asignal incidence counter identifying a number of times a signal has beenreceived by said receiver at each geographic location.
 44. The policewarning receiver of claim 38 wherein said information relating torejectable electromagnetic signals comprises flags associated withgeographic locations, said flags identifying rejectable signals at eachgeographic location.
 45. The police warning receiver of claim 38 furthercomprising an interface connector, wherein information relating torejectable electromagnetic signals is stored in said storage via saidinterface connector.
 46. The police warning receiver of claim 45 whereinsaid interface connector complies with one of a universal serial busstandard, an automotive wiring standard, the J1862, CAN, BH12 and LINstandards.
 47. The police warning receiver of claim 38 adapted to accessand store said information relating to prior encounters from externalsources.
 48. The police warning receiver of claim 47 further comprisingcommunication circuitry for obtaining said signal information from anInternet resource.
 49. The police warning receiver of claim 47 furthercomprising communication circuitry for obtaining said signal informationfrom a general purpose computer.
 50. The police warning receiver ofclaim 47 further comprising communication circuitry for obtaining saidsignal information from another police warning receiver.